Dishwasher for kosher operation

ABSTRACT

The invention relates to an automatic dishwasher ( 1 ) which can be operated in several operating modes ( 71, 72, 73, 74 ). The automatic dishwasher ( 1 ) proposed according to the invention can be switched from a first operating mode ( 71 ) to a second operating mode ( 72 ) only when a third operating mode ( 73 ) called kosher operation is executed. During the third operating mode ( 73 ) “Kosher operation”, the interior of the automatic dishwasher ( 1 ) is cleaned with a heated cleaning fluid whose temperature lies above the maximum temperature occurring in the normal operation of the automatic dishwasher ( 1 ). The endless conveyor belt ( 10 ) of the automatic dishwasher ( 1 ) is treated by a cleaning device ( 43 ) during the third operating mode ( 73 ) “Kosher operation”; moreover, a water tank ( 25 ) of the automatic dishwasher ( 1 ) is heated to a higher temperature than the temperature which occurs in the normal operation of the automatic dishwasher ( 1 ). In an operating mode called “Sabbath operation”, the current to the drive mechanism of the automatic dishwasher is interrupted via a light barrier ( 52 ).

TECHNICAL FIELD

The invention relates to a dishwasher, in particular a belt-typedishwasher used for commercial purposes. The dishwasher proposedaccording to the invention can be used both in kosher operation and alsoon religious holidays such as the Sabbath.

PRIOR ART

The company brochure entitled “Geschirrspülautomat mit Bandtransport”[Automatic dishwasher with conveyor belt] from the company MeikoMaschinenbau GmbH & Co. KG No. 2031.03.03/KD/4.000D discloses a conveyorbelt automatic dishwasher in which the material to be cleaned istransported on an endless conveyor belt. The material to be cleaned isplaced on the conveyor belt at the machine inlet and first passesthrough a dirt removal area. By means of spray nozzles from which thematerial to be cleaned is sprayed with water jets from the underside andfrom above, food residues falling down in the dirt removal area arecleared away. The machine inlet is covered by a hood. Located underneaththe conveyor belt there are one or more coarse sieves which trap thefalling food residues. The smallest food residues can be collected via afine sieve arranged under the coarse sieve(s). Located below the finesieve, there is in turn a collecting vessel for the rinse water drippingfrom the removed dirt.

Viewed in the direction in which the material to be cleaned is conveyed,the machine inlet and the adjoining rough cleaning area are followed byseveral rinse zones lying one after the other. Inside these rinse zones,the material to be cleaned is treated with hot rinse water. The hotrinse water issues both from spray nozzles arranged underneath theendless conveyor belt and also from spray nozzles which rinse thematerial from the top. After passing through a first rinse zone, thematerial to be cleaned is conveyed by the endless conveyor belt into atleast one further rinse zone in which it is likewise rinsed by beingsprayed. The rinse water issuing from the spray nozzles in said rinsezones is heated to a higher temperature at which the material placed onthe endless conveyor belt is rinsed off. After the second rinse zone,the material to be cleaned can be transported either into a final rinsezone or into a further rinse zone.

A collecting vessel of cascade-like configuration is provided underneaththe rinse zones and the final rinse zone. The collecting vessel isdivided into individual segments by individual dividing walls. Thedividing walls are dimensioned such that, when a certain water level isreached in each segment, an overflow of the rinse water into thepreceding segment is ensured. Each segment of the rinse water tank isassigned a wash pump with which from the respective segment of the rinsewater storage tank, after previous filtering of the wash liquor, rinsewater is delivered to the individual spray nozzles of the respectiverinse zone or final rinse zone.

Downstream of the final rinse zone of the known automatic conveyor belt,there is a heat recovery unit, which can optionally be assigned anexhaust air cleaning unit. This unit is followed by a drying fan viawhich warm air can be applied to the cleaned and rinsed material, sothat the latter is dried and cooled as it goes through the dryingprocess. The drying station is followed by an outlet for the dishes, atwhich outlet the cleaned, rinsed and dried dishes can be removed fromthe automatic conveyor belt either manually or in an automated manner.On the operator side of the automatic conveyor belt known from saidcompany brochure, the individual rinse zones are accessible via screenswhich can be put up. Under the screens there are curtain elements withwhich the individual rinse zones are provided in order to prevent spraywater escaping to the sides. In automatic dishwashers with a conveyorbelt, it is standard practice for one set of curtains to be provided perrinse zone.

Kosher food is defined in accordance with Jewish religious law, which isset down in the Torah, the centerpiece of the Jewish faith. The wordkosher signifies everything that has been produced or prepared accordingto Jewish law. Kosher diet follows the rules of kashrut (Jewish dietarylaws). In accordance with kashrut, only four-footed animals that chewtheir cud and have cloven hooves may be eaten. This excludes pigs orhares, for example. Poultry, by contrast, is kosher.

Of fish, only those that have fins and scales may be eaten. The fifthBook of Moses is the basis of the prohibition on eating meat at the sametime as milk or milk products. After eating meat, 6 hours must passbefore a milk product is eaten or drunk. The rules also include usingseparate pots, cutlery and dishes for these foods. The Torah, as thecenterpiece of Jewish faith, further prohibits the consumption of blood.Meat must be treated in a special way, by which is meant extractingexcess blood, then washing the meat and subsequently sprinkling it withsalt. This way of treating meat also involves a ritual method ofslaughter, namely kosher slaughter.

In view of these underlying principles of the Jewish faith, it washitherto necessary to ensure that dishes which came into contact withmilk products were cleaned in one dishwasher and that dishes which cameinto contact with meat or meat products were rinsed and cleaned inanother dishwasher separate from the first one. This means aconsiderable outlay in terms of the work involved, the investment costsand the space taken up, in order to comply with the dietary laws ofkashrut as regards the cleaning of dishes.

A further precept of Jewish faith commands that no flame be kindledduring the Sabbath. Actuating an electric switch is equated to kindlingflame. However, the operation of electrically driven machines requires,irrespective of the operating states, or in the event of a malfunction,the intervention of a machine operator, which nowadays entails actuatinga switch. If a dishwasher such as the conveyor belt dishwasher knownfrom the aforementioned company brochure is operated during the Sabbath,malfunctions will result in the electrically driven dishwasher shuttingdown for quite long periods, the possible consequence of which isconsiderable down times if immediate intervention is not possible,because to intervene would require actuation of an electric switch.

DISCLOSURE OF THE INVENTION

In view of the precepts of the Jewish faith outlined above, the objectof the invention is to design a dishwasher, in particular a dishwasherwhich can be used on a commercial scale, in such a way that dishes whichhave been in contact with milk products and dishes which have been incontact with meat can be cleaned in one and the same dishwasher, and thesame dishwasher can also be operated without disruption during theSabbath or other Jewish holy days.

According to the invention, this object is achieved by the features ofpatent claim 1.

The main advantage of the solution proposed according to the inventioncan be seen to be the fact that different types of dishes can now becleaned in one and the same commercially usable dishwasher, this beingunderstood to mean, in particular, dishes which have previously been incontact with milk products and also dishes which have been in contactwith meat or meat products. By performing a “Kosher cleaning operation”between an operating mode in which dishes that have been in contact withmilk products are cleaned and an operating mode in which dishes thathave been in contact with meat or meat products are cleaned, a kosheroperation is conducted, after which the entire machine is cleaned with acleaning fluid. In accordance with the precepts of Jewish faith, thecleaning fluid is brought to a temperature which is up to 10° C. abovethe maximum temperature that occurs in the normal operation in thedishwasher.

Moreover, the automatic dishwasher with conveyor belt that can be usedby those of the Jewish faith also comprises a cleaning system whichserves to clean the endless conveyor belt carrying the material to becleaned. This belt remains in the automatic dishwasher during theoperating mode “Cleaning of dishes having been in contact with milkproducts” and also during the operating mode “Cleaning of dishes havingbeen in contact with meat or meat products” in the machine, and it iscleaned by a cleaning device during the kosher operation. A cleaningstep for cleaning the belt takes place between the manual cleaning ofthe machine and a “Kosher operation”. This can be done, for example, bycleaning brushes assigned to the endless conveyor belt. These arearranged in such a way that the endless conveyor belt is brushed cleanby cleaning brushes both from the top and also from underneath. Theendless conveyor belt is made from plastic and is built permanently intothe automatic dishwasher. It constitutes a large plastic component thatcannot be exchanged. However, to be able to use the endless conveyorbelt remaining in the automatic dishwasher both in the operating mode“Cleaning of dishes having been in contact with milk products” and alsoin the operating mode “Cleaning of dishes having been in contact withmeat or meat products”, the endless conveyor belt is brushedmechanically prior to the “Kosher operation”.

The dishwasher which is proposed according to the invention, and whichcan be used by those of the Jewish faith, also comprises a curtain whichcan be suspended into the individual rinse zones and is exchangeable andwhich, during the kosher operation, when switching between one of theoperating modes “Cleaning of dishes having been in contact with milkproducts” and “Cleaning of dishes having been in contact with meat ormeat products”, is suspended as curtain into the individual rinse zonesthat are accessible from the operator side of the automatic dishwasher.

In view of the kosher laws of the Torah, the centerpiece of Jewishfaith, provision can also be made for the rinse water tank of theautomatic dishwasher according to the invention to be heated to atemperature which is above the maximum rinse water temperature or freshwater temperature occurring in the normal operation of the dishwasher.In this context, it is also possible to describe the interior of thewater tank of the automatic dishwasher as being made kosher.

In the machine control unit of an automatic dishwasher of this design,switching from the operating mode “Cleaning of dishes for milk products”and “Cleaning of dishes for meat/meat products” is possible only when a“Kosher operation” has taken place and the endless conveyor belt hasbeen cleaned between the switching between said operating modes. Directswitching from one operating mode of the automatic dishwasher accordingto the invention to the respective other operating mode is not possibleand is prevented by the machine control unit.

In the machine control unit, a further implementation is that during theSabbath, so as to avoid kindling a flame, i.e. by actuation of anelectric switch by an operator, the proposed automatic dishwasherswitches off automatically in emergency situations. In the Sabbathoperating mode, it must be ensured that, if a malfunction occurs, thedishwasher is switched off automatically by the machine control unit,without an operator having to do anything. Thus, for example, theautomatic conveyor belt drive can be switched off by means of the factthat, in the absence of a reflected optical signal in a light barrier,the forward movement of the belt and the pump operation are switched offwithout requiring the intervention of an operator.

For the Sabbath operating mode, it is provided that the conveyor beltautomatic dishwasher runs at a certain speed in respect of the forwardmovement of the endless conveyor belt. For each operating mode, i.e. for“Cleaning of dishes having been in contact with milk products” and“Cleaning of dishes having been in contact with meat or meat products”,timers are built in. The automatic dishwasher is rendered operativethrough the operation of a switch, which can be designed for example asa key switch. The actual start-up of the automatic dishwasher during theSabbath is effected by the timer assigned to the respective operatingmode.

In accordance with the selected operating mode, the first curtainsassigned to this for the operating mode “Cleaning of dishes having beenin contact with milk products” or the second curtains for the operatingmode “Cleaning of dishes having been in contact with meat or meatproducts” are suspended into the automatic dishwasher. The automaticdishwasher begins in the respective operating mode with the function offilling or heating of the water tank. After the desired temperature isreached, the actual rinse procedure begins in the respectively selectedoperating mode, until the timer stops the operating mode. Thereafter,the curtains assigned to the respective operating mode are replaced bythe curtains required in the operating mode “Kosher operation”, becausea “Kosher operation” is necessary. When the timer assigned to thepreceding selected operating mode switches off, the “Kosher operation”is thus triggered. At the end of the “Kosher operation”, a rinseprocedure is started anew depending on the setting of the timers for theoperating mode “Cleaning of dishes having been in contact with milkproducts” or the operating mode “Cleaning of dishes having been incontact with meat or meat products”. To operate the automatic dishwasheragain on workdays, the Sabbath operating mode has to be switched off viathe corresponding switch.

If, during the Sabbath operating mode, there is a power outage or a mainswitch off state, the automatic dishwasher switches back to the normalSabbath operating mode once voltage has been recovered after the poweroutage, and the automatic dishwasher begins the program sequence withfilling/heating of the water tanks.

If a belt limit switch is activated during the Sabbath operating mode,which happens when a dish not removed from the endless conveyor beltstrikes against a limit switch function, the drive mechanism of theendless conveyor belt is switched off. In this way, a light barrier isswitched to a voltageless state. In a cycle of, for example, 15 seconds,the supply voltage of the light barrier is switched on by a shortimpulse. If it is thus detected that the limit switch is free again, thedrive mechanism of the endless conveyor belt switches on. By contrast,if the limit switch is detected as being not yet free, the supplyvoltage is cut out again for a period of about 15 seconds. In the caseof an emergency off function, which can occur through actuation of thecorresponding switch, the automatic dishwasher switches off completely.The emergency off switch is switched to a voltageless state. The supplyvoltage of the emergency off switch is switched back on every 60 secondsby a short impulse. When the emergency off switch is released again, theautomatic dishwasher resumes the rinse program with a step “Start rinseoperation on Sabbath”. If the emergency off switching in the Sabbathoperating mode takes place during the “Kosher operation”, the operatingmode “Kosher operation” then continues as normal after disconnection ofthe emergency off switch. If, at the time of the emergency offswitching, the automatic dishwasher is in the operating mode “Sabbathoperation” and is there in a wash program, the machine program resumeswith the step “Heating prior to kosher operation” after the emergencyoff switch has been disconnected.

By contrast, if the emergency off switch is not released, the voltagesupply is again cut off for a period of about 60 seconds.

If overloading of the endless conveyor belt is detected in the Sabbathoperation of the automatic dishwasher, as may happen for example if adish or cutlery blocks the forward movement of the belt, the rinseoperation is automatically switched off. The belt overload switch isswitched to a voltageless state. It is switched back on again, forexample within a time slot of 30 seconds, by means of a short impulse ofthe supply voltage. If the belt overload switch is disconnected, therinse operation begins again after a hooter sound. By contrast, if thebelt overload switch is not disconnected, the supply voltage is cut outfor a time slot of 30 seconds. This cycle of switching on and off of thebelt overload switch will take place up to 3 times. If, after the thirdoccasion, the belt overload switch is detected as still not being free,the cycle is increased to 5 minutes. When this cycle of 5 minutes hasalso taken place 3 times without success, the automatic dishwasherswitches off completely and can no longer be started automatically inthe Sabbath operating mode.

DRAWING

The invention is described in more detail below with reference to thedrawing, in which:

FIG. 1 shows a cross section through an automatic dishwasher equippedaccording to the invention and with a conveyor belt,

FIG. 2 shows the overflow or outflow system of a conveyor belt automaticdishwasher,

FIG. 3 shows the machine outlet with a movably mounted limit switch,

FIG. 4 shows the view of a light barrier arrangement,

FIG. 5 shows the connection between a mirror surface and a limit switch,

FIG. 6 shows a deflected limit switch, and

FIG. 7 shows a control panel for a machine control unit of an automaticdishwasher according to the view in FIG. 1.

EMBODIMENT VARIANTS

The view according to FIG. 1 shows an automatic dishwasher with conveyorbelt. At the machine inlet 2, the material to be cleaned is placed on anendless conveyor belt 10. The endless conveyor belt 10 is movedcontinuously by means of a drive mechanism 24 arranged in the area of anoutlet 23 for the dishes and conveys the material to be cleaned throughthe conveyor belt automatic dishwasher. Inside a rough cleaning area 3,large residues of food are rinsed off and fall into a coarse sieve 4arranged under the endless conveyor belt 10, under which coarse sieve 4a fine sieve 5 can optionally be arranged. Underneath the fine sieve 5there is a common outflow 6 in which the rinsing water is collected.After passing through the rough cleaning area 3, the material to becleaned is transported into a first rinse zone 7, which can be followedby a second rinse zone 8 or even by several further rinse zones. Thedishes cleaned beforehand in the first rinse zone 7 and in the secondrinse zone 8 or the further rinse zones are then given a final rinse ina final rinse zone 9. The endless conveyor belt 10 is fed through theconveyor belt automatic dishwasher 1 in the direction of advance 11.

In the first rinse zone 7, there are upper spray nozzles 13 above thematerial to be cleaned, and lower spray nozzles 12 under the endlessconveyor belt 10, via which nozzles the material to be cleaned issprayed with rinse water. During the operation of the conveyor beltautomatic dishwasher 1, the first rinse zone 7 is closed laterallyagainst escaping spray water. Viewed in the direction of advance 11 ofthe material to be cleaned, a preliminary clearing area 3 is closed offby a first curtain 40 against outwardly escaping spray water. The firstrinse zone 7 following on from the preliminary clearing area 3 isseparated by a further first curtain 40 from the second rinse zone 8 atwhose outlet—seen in the direction of advance 11 of the material to becleaned—there is a further first curtain 40. The final rinse zone 9following on from the second rinse zone and comprising a pump finalrinse 31 and a fresh water final rinse 32 is delimited from a heatrecovery module 17 by a further first curtain 40. Downstream of thedrying zone 22 there is a further first curtain 40 with which the dryingzone 22 is screened off from the outside in the direction of the outlet23 for the dishes. Situated underneath the first rinse zone 7 there is asegment of a water tank 25. The segment of the water tank 25 assigned tothe first rinse zone 7 is separated by a dividing wall 26 from othersegments of the water tank 25. Situated on the bottom of the water tankassigned to the first rinse zone 7 there is a circulating pump 29 forthe rinse water, which pump is assigned a filter 30. The individualdividing walls 26 which divide the water tank 25 into individualsegments assigned to the rinse zones 7 and 8 or the final rinse zone 9can, for example, be designed as sheet metal walls.

The lower and upper spray nozzles 12, 13 are supplied with circulatedrinse water via the circulating pump 29 assigned to the first rinse zone7.

After passage through the first rinse zone 7, as the endless conveyorbelt 10 moves in the direction of advance 11, the material to be cleanedwhich is received on said conveyor belt moves into a second rinse zone8. Inside the second rinse zone 8 there are upper spray nozzles 15 andlower spray nozzles 14. By means of these spray nozzles, the material tobe cleaned is subjected to further rinsing inside the second rinse zone8 with rinse water which is brought to an increased temperature. Whilethe temperature of the rinse water received in the water tank 25 and ofthe heated fresh water introduced into the final rinse zone 9 is about80° C. to 85° C., the water sprayed inside the preliminary clearing area3 has a temperature of maximum 42° C., which satisfies kosherrequirements. A lower temperature of the water sprayed inside thepreliminary clearing area 3 would entail the disadvantage of fatgathering on the material to be cleaned.

The second rinse zone 8 is also assigned a segment of the water tank 25on whose base a circulating pump 29 with associated filter 30 isreceived. The upper spray nozzles 15 and the lower spray nozzles 14 aresupplied with rinse water via this circulating pump 29 assigned to thesegment of the water tank 25 for the second rinse zone 8.

In the direction of advance 11 of the material to be cleaned, the secondrinse zone 8 is followed by a final rinse zone 9. The material cleanedbeforehand in the first rinse zone 7 and in the second rinse zone 8 issubjected to a final rinse inside the final rinse zone 9 with additionof a rinse aid, so that the material to be cleaned is cleanedstain-free. The final rinse zone 9 is also assigned a pump with whichthe spray nozzles in the final rinse zone 9 are supplied with freshwater, possibly with addition of a cleaner or rinse aid. In the finalrinse zone 9 there is a pump final rinse 31 and a pure fresh water finalrinse 32.

In the direction of advance 11 of the material to be cleaned, the finalrinse zone 9 is followed by a heat recovery module 17 in which a coolingregister 18 is received. The heat recovery module 17 additionallycomprises a fan 19.

Downstream of the heat recovery module 17 there is a drying module 20 inwhich a hot air dryer 21 designed as a fan is arranged. As it passesthrough the drying zone 22, the cleaning material received on theendless conveyor belt 10 and previously cleaned and rinsed is dried andcooled so that it can be removed from the endless conveyor belt 10 atthe outlet 23 for the dishes. The drive mechanism 24 (not shown indetail in FIG. 1) for the endless conveyor belt 10 is also accommodatedin the outlet area 23 for the dishes.

In addition, the conveyor belt automatic dishwasher 1 according to theinvention comprises a cleaning device 43 with which the endless conveyorbelt 10 made of plastic and accommodated in the machine can be cleanedboth on its upper face and also on its lower face. The cleaning device43, formed by a pair of oppositely arranged brushes, is disposed betweenthe pump final rinse 31 and the fresh water final rinse 32.

In addition, the conveyor belt automatic dishwasher 1 according to theview in FIG. 1 comprises a limit switch 50 which is assigned a firstlight barrier 52, and a further, second light barrier 52 which detectsoverloading of the drive mechanism 24 of the endless conveyor belt 10and switches off the drive mechanism 24, for example if an item to becleaned obstructs the movement of the endless conveyor belt 10.

When the conveyor belt automatic dishwasher 1 shown in FIG. 1 is used inthe operating mode “Cleaning of dishes for milk products”, the firstrinse zone 7 and the second rinse zone 8 and the entry side in the areaof the machine inlet 2 and the exit side in the area of the outlet 23for dishes are protected by first curtains 40. Accordingly, in thisoperating mode, spray water contaminates only the first curtains 40.

In the operating mode “Cleaning of dishes for meat/meat products”, thefirst curtains 40 are replaced by second curtains 41 which accordingly,in this operating mode, by virtue of the spray water created there, comeinto contact with the spray water created in this operating mode.

Switching from one of said operating modes to the respective otheroperating mode is prohibited by the machine control system in conveyorbelt automatic dishwashers used by people of the Jewish faith. Beforeswitching the operating mode, an operating mode called “Kosheroperation” is enforced which necessitates changing the first curtains 40in the automatic dishwasher 1 for the operating mode “Cleaning of dishesfor milk products” or the second curtains 41 for the operating mode“Cleaning of dishes for meat/meat products” by suspension of a thirdcurtain 42 for the operating mode called “Kosher operation”. In thecontext of the operating mode called “Kosher operation”, the thirdcurtains 42 are suspended only at the inlet to the preliminary clearingarea 3 in the region of the machine inlet 2 and downstream of the dryingzone 22 at the exit to the outlet 23 for the dishes.

In the operating mode “Kosher operation”, which is enforced whenswitching from said operating modes for “Cleaning of dishes for milkproducts” and “Cleaning of dishes for meat/meat products”, the whole ofthe interior of the conveyor belt automatic dishwasher 1 is cleaned witha cleaning medium which is heated to up to 90° C. to 95° C., that is tosay to a temperature which is higher than the operating temperature ofabout 85° C. which is the maximum that occurs in the operation of theconveyor belt automatic dishwasher 1. By cleaning the whole of the innerarea of the conveyor belt automatic dishwasher 1 coming into contactwith spray water, according to the view in FIG. 1, it is possible toensure, in accordance with the customs of the Jewish faith, that anyfood residues or spray water residues which could be tainted either withmilk product residues or meat product residues are removed and theconveyor belt automatic dishwasher 1 is kosher within the meaning of theJewish faith.

In the operating mode “Kosher operation”, the endless conveyor belt 10is also cleaned by a cleaning device 43 so that both the lower face ofthe endless conveyor belt 10 and also its upper face are brushed cleanmechanically. In this way, the endless conveyor belt 10 consisting ofindividual plastic components is kosher within the meaning of the Jewishkashrut.

The replacement of the first curtains 40 and second curtains 41 by athird curtain 42 to be used only in the operating mode “Kosheroperation” prevents contamination of the respective curtain in theoperating mode “Cleaning of dishes for milk products”, i.e. of the firstcurtains 40 or the second curtains 41 which, in the operating mode“Cleaning of dishes for meat/meat products”, are suspended at theappropriate suspension positions of the conveyor belt automaticdishwasher 1.

Heating the water tank 25 in the operating mode “Kosher operation”ensures that its content too is kosher within the meaning of kashrut.

The conveyor belt automatic dishwasher 1 shown in FIG. 1 has a limitswitch 50 which triggers automatic switching-off of the drive mechanism24 of the endless conveyor belt 10. The limit switch 50 is assigned afirst light barrier 52, while the drive mechanism 24, which ispreferably mounted on a rocker, is assigned a second light barrier 52.Said first and second light barriers 52 are described in more detail inconnection with the operating mode called “Sabbath operation”.

FIG. 2 shows the overflow or outflow system of a conveyor belt automaticdishwasher suitable for kosher operation. In the area of the final rinsezone 9, a first filling line 47 from a fresh water connection (notshown) opens into the inside of the segment of the water tank 25underneath the final rinse zone 9. A valve 49 is accommodated in thefirst filling line 47. The dividing wall of the segment of the watertank 25 underneath the final rinse zone 9 is designed as an overflow 28,so that water can overflow like a cascade into the segment of the watertank 25 underneath the second spray zone 8. The dividing wall 26 of thesegment underneath the second final rinse zone 8 is likewise designed asan overflow 28. The water flows via this overflow 28 into the segment ofthe water tank 25 underneath the first rinse zone 7. The segment of thewater tank 25 underneath the first rinse zone 7 comprises a secondoutflow 46 since the segment of the water tank 25 underneath the firstrinse zone 7 is separated from the preliminary clearing area 3 by adividing wall 33.

The filling of the segment of the water tank 25 underneath thepreliminary clearing area 3 is effected via a second filling line 48into which a valve 49 is likewise incorporated. The outflow of the waterfrom the segment of the water tank 25 underneath the preliminaryclearing area 3 is effected via an outflow 45 which opens into thecommon outflow 6 of the conveyor belt automatic dishwasher 1. The wastewater of the conveyor belt automatic dishwasher flows via this into awaste water system.

Each of the segments of the water tank 25 is assigned a circulating pump29 and a filter 30. The supply of fresh water to the preliminaryclearing area 3 via the second filling line 48 takes place separately.The water used in the preliminary clearing area 3 only has a temperatureof at maximum 42° C., whereas the water sprayed into the first rinsezone 7 and into the second rinse zone 8 and into the final rinse zone 9has a temperature in the range of between 55° C. and 85° C.

The conveyor belt automatic dishwashers 1 shown in each case in crosssection in FIGS. 1 and 2 have a division of the tank segment of thepreliminary clearing area 3 in respect of the cascade water flowing overvia the overflows 28 from the segments of the storage tank 25 of thefirst rinse zone 7 and of the second rinse zone 8 and the final rinse 9.Accordingly, the conveyor belt automatic dishwasher has two outflows 45,46. The waste water is brought together in the common outflow 6 outsidesaid tanks. The distance between the last washing arm of the preliminaryclearing area 3 and the tank division 33 is at least 40 cm. The segmentof the storage tank 25 assigned to the preliminary clearing area 3 hasits own separately controlled tank heater, since the temperature of thewater used in the preliminary clearing area 3 in rinse mode must notexceed a temperature of 42° C. In the conveyor belt automatic dishwasher1 proposed according to the invention, there are no rinse temperatureshigher than 85° C. The limit switch 50 is interrogated not via asolenoid switch, but via a first light barrier 52. Two sets of lower andupper belt brushes are used as cleaning device 43, these being arrangedbetween the pump final rinse 31 and the fresh water final rinse 32. Inrespect of an automatic program sequence in the operating mode “Sabbathoperation”, the waste water pumps used are provided in all segments ofthe storage tank 25.

Whereas in the operating mode “Sabbath operation” of the conveyor beltautomatic dishwasher 1, the operating mode “Kosher operation” isautomatically started after each rinse operation, outside the Sabbath,i.e. on normal weekdays, the operating mode “Kosher operation” isstarted manually. For this purpose, the third curtains 42 have to besuspended before the start of the operating mode “Kosher operation”. Thekosher process then starts, the outflow pumps are activated, an overruntime of the outflow pumps of about 2 minutes being guaranteed. During asubsequent time interval of approximately 30 minutes, the belt conveyorautomatic dishwasher 1 can be cleaned manually. During theabovementioned time interval of 30 minutes needed for the manualcleaning, the outflow pumps pump cyclically (cycle: every 2 minutes for30 seconds). Thereafter, the cleaning device 43 is used which can bedesigned as a pair of brushes which in each case brush clean the upperface and the lower face of the endless conveyor belt 10. The endlessconveyor belt 10 runs at the maximum speed and the final rinse insidethe final rinse zone 9 is in operation. This process step lasts for twocomplete revolutions of the endless conveyor belt 10 at the maximumspeed. During the belt-cleaning process, the outflow pumps pump thewater off. After the belt-cleaning process is completed, the conveyorbelt automatic dishwasher 1 is filled and the water is heated to akosher temperature of about 95° C. Once the kosher temperature has beenreached in each of the segments of the storage tank 25, the operatingmode “Kosher operation” starts. This means that the circulating pumps29, the drive mechanism of the endless conveyor belt 10 and the exhaustair suction are in operation. The duration of the operating mode “Kosherprocess” is limited to two complete belt revolutions at a medium machinespeed. Thereafter, all segments of the storage tank 25 are emptied. Thisis followed by removal of the cleaning device 43 and withdrawal of thethird curtains 42 at the machine inlet 2 and at the outlet 23 for thedishes.

The operating mode “Kosher operation” which runs between the operatingmode “Cleaning of dishes for milk products” and the operating mode“Cleaning of dishes for meat/meat products” cannot be interrupted,except in workday operation where an interruption can be brought aboutby opening a door. If the program sequence is interrupted during theoperating mode “Kosher operation” upon filling/heating of the storagetank 25, which may happen for example by opening a door, the conveyorbelt automatic dishwasher 1 continues to fill and heat. If the programsequence is interrupted during the operating mode “Kosher operation”,the pumps and the drive mechanism 24 switch off. If the doors on theconveyor belt automatic dishwasher 1 are closed again, the operatingmode “Kosher operation” continues exactly from the point at which it wasinterrupted. In the operating mode “Sabbath operation”, the doorswitches monitoring opening of the door are non-operational, so that theoperating mode “Kosher operation” is not interrupted by opening the doorin the operating mode “Sabbath operation”. If the operating mode “Kosheroperation” is interrupted by the emergency off switch, the conveyor beltautomatic dishwasher 1 is completely switched off. After releasing theemergency off switch, the conveyor belt automatic dishwasher 1 continuesexactly from the point at which it was stopped. However, if the conveyorbelt automatic dishwasher 1 was situated at washing in the operatingmode “Kosher operation”, the program begins again with the step ofheating the water before the “Kosher operation”.

A fully terminated operating mode “Kosher operation” must always beinterposed between the washing of dishes for milk and washing of dishesfor meat. When a rinse process according to the operating mode for meator milk is started, a light indicating “Kosher operation” goes off on acontrol panel. The machine control unit always registers the last rinseprocess carried out, even in the event of a power failure. Aftercarrying out a “Kosher operation”, it is not generally customary torepeat the preceding rinse process. However, if this were to bedesirable in exceptional cases, the start button for the correspondingrinse program must be pressed for at least 5 seconds. It must not bepossible at any time to switch from the operating mode “Cleaning ofdishes for milk products” to the operating mode “Cleaning of dishes formeat/meat products” or vice versa without cleaning the conveyor beltautomatic dishwasher 1 by means of the operating mode “Kosheroperation”.

FIG. 3 shows the outlet area of the machine, with a movably arrangedlimit switch.

The endless conveyor belt 10 made of plastic material reverses in thearea of the outlet 23 for the dishes. A dish 51, indicated on theendless conveyor belt 10, has not been removed at the outlet 23 fordishes and, accordingly, strikes against the movably mounted limitswitch 50. The latter pivots away and thus triggers a shutdown of thedrive mechanism 24 of the endless conveyor belt 10. The direction ofadvance of the endless conveyor belt 10 is indicated by the arrow 11.

FIG. 4 shows the view of a light barrier arrangement assigned to themovably mounted limit switch. A first light barrier 52 is positionedunderneath the outlet 23 for dishes from the conveyor belt automaticdishwasher 1. This light barrier 52 is received on a housing 54. Forreasons of clarity, the movably mounted limit switch 50 is notreproduced in FIG. 4. The first light barrier 52, which is secured onthe outside of the housing 54, communicates with the machine controlunit via a connecting line 55. Formed in the housing 54 of the limitswitch arrangement there is a circular opening 58 behind which a movablymounted mirror surface 53 lies. In the non-deflected state of the limitswitch, the mirror surface 53 reflects light emanating from the firstlight barrier 52. The drive mechanism 24 of the endless conveyor belt 10remains in operation. It is only when a dish 51 not removed from theendless conveyor belt 10 strikes against the limit switch 50 that themirror surface 53 lying behind the opening 58 pivots away and thereflection of the emitted light beams is interrupted by the first lightbarrier 52.

FIG. 5 shows the connection between a mirror surface and the movablymounted limit switch.

In the lower area, the movably mounted limit switch 50, indicated by thedouble arrow according to FIG. 5, has a bracket 56. The bracket 56 isconnected to the machine frame of the conveyor belt automatic dishwasher1 via a restoring spring 57. The mirror surface 53 is secured on thebracket 56. If the movably mounted limit switch 50 is deflected downwardin the direction of the double arrow, for example by a dish 51 strikingagainst it, this results in a pivoting movement of the bracket 56 and,accordingly, a pivoting away of the mirror surface 53 secured on thebracket 56. This mirror surface thus drops from the opening 58 of thehousing 54 according to FIG. 4, so that no light is thrown back onto thefirst light barrier 52.

A switching-off of the drive mechanism 24 of the endless conveyor belt10 is thus triggered.

FIG. 6 shows a deflected limit switch. In addition to the function ofswitching off the drive mechanism 24 of the endless conveyor belt 10, anoverload function is also provided on the conveyor belt automaticdishwasher 1 proposed according to the invention. For this purpose, thedrive motor 59 is mounted on a tilt bearing 60. The drive motor 59, viaa belt or chain drive, moves a guide wheel of the endless conveyor belt10 in the area of the outlet 23 for dishes from the conveyor beltautomatic dishwasher 1. If its forward movement in the direction ofadvance 11 is impeded by a dish 51 that has not been removed or by anitem of cutlery or dish that has been left in the inside of the conveyorbelt automatic dishwasher 1, the drive motor 59 is deflected from itsnormal position on the tilt bearing 60. Because of this, a mirrorsurface 53 connected to the drive motor 59 moves out from the area of asecond light barrier 52 shown in FIG. 1, such that the drive motor 59can also be switched off in the event of overloading of the endlessconveyor belt 10.

The view according to FIG. 7 shows a control panel of a conveyor beltautomatic dishwasher which is able to execute a separate operating mode“Kosher operation” and an operating mode “Sabbath operation”.

The conveyor belt automatic dishwasher 1 shown in FIG. 1 is operated bymeans of the control panel 70 shown in FIG. 7. The operating mode“Cleaning of dishes for milk products” is switched on via the firstswitch 71. In this operating mode, the conveyor belt automaticdishwasher 1 is provided with the first curtains 40. After completion ofa cleaning program, i.e. a complete passage of the material to becleaned through the conveyor belt automatic dishwasher 1, it isprohibited to switch directly to the operating mode “Cleaning of dishesfor meat/meat products” which can be triggered via a second switch 72.Direct switching from one operating mode to the other operating mode isnot possible. This is ensured by the fact that switching from oneoperating mode to the other, and vice versa, requires the execution ofthe operating mode “Kosher operation”. To trigger the operating mode“Cleaning of dishes for meat/meat products”, actuation of the thirdswitch 73 for the operating mode “Kosher operation” is imperative.Depending on the preceding operating mode of the conveyor belt automaticdishwasher 1, the first curtains 40 and second curtains 41 suspendedtherein are first withdrawn and are replaced by the third curtains 42that are to be used exclusively in the operating mode “Kosheroperation”. After use of the third curtains 42 for the operating mode“Kosher operation”, the areas contaminated by spray water in thepreceding operating modes of the conveyor belt automatic dishwasher 1are cleaned by a cleaning fluid which is heated to a temperature ofabout 90° C. to 95° C., that is to say a temperature which is 5° C. to10° C. above the maximum temperature occurring in the normal operationof the conveyor belt automatic dishwasher 1. Moreover, in the operatingmode “Kosher operation”, the endless conveyor belt 10, consisting ofindividual plastic components interconnected in an articulated manner,is cleaned by a cleaning system 43 in the form of brushes, so as to bekosher within the meaning of kashrut. Moreover, during the operatingmode “Kosher operation”, the inside of the water tank 25 is heated alsoto a temperature which is above the maximum temperature of the rinsewater or fresh water sprayed in the conveyor belt automatic dishwasher1.

Moreover, the control panel 70 shown in FIG. 7 comprises a fourth switch74 which can be actuated, for example, by means of a key or such like.Using the fourth switch 74, the conveyor belt automatic dishwasher 1according to the view in FIGS. 1 and 2 can be converted to an operatingmode suited for Jewish holy days, for example the Sabbath. When theconveyor belt automatic dishwasher 1 is switched to this operating modeby actuation of the fourth switch 74, the conveyor belt automaticdishwasher 1 runs substantially automatically, although manualintervention is permitted, and it switches itself off automatically ifmalfunctions occur. If the conveyor belt automatic dishwasher 1 isoperated during the Sabbath, i.e. in the period from Friday to Saturday,it is thus ensured that the conveyor belt automatic dishwasher 1switches off automatically, in the event of a malfunction of the forwardmovement of the endless conveyor belt 10, by means of automaticswitching-off of the drive mechanism 24, with the result that no damagecan occur. Limit switches, with which the forward movement of theendless conveyor belt 10 in the direction of advance 11 is monitored,can be assigned both to the tilt bearing 60 of the drive motor 59 andalso to the limit switch 50. The limit switches are preferablyconfigured as first and second light barriers 52. The light barriers 52emit a light beam onto a mirror surface 53 which is mounted so as to beable to deflect and which is arranged on a bracket 56. If the bracket 56is deflected because a dish 51 is blocking the forward movement of theendless conveyor belt 10, the mirror 53 reflecting the light beamemitted by the light barrier 52 is deflected from the area of the lightbarrier 52, such that the receiver part of the light barrier 52 does notsense any reflected beam. By virtue of the absence of the reflectedlight beam, the drive mechanism 24, 59 of the endless conveyor belt 10is switched off. After removal of the dish obstructing the forwardmovement of the endless conveyor belt 10, the deflecting mirror resumesits original position and the conveyor belt automatic dishwasher 1resumes its operation.

By virtue of the fourth switch 74 for the operating mode “Sabbathoperation”, operating mode of the conveyor belt automatic dishwasher,there is no electrical switching function that has to be performed by aperson operating the dishwasher. Everything runs automatically. A clockcircuit provided in the context of the machine control unit isnon-operational; the door switches are also rendered non-operational. Inthe operating mode “Sabbath operation”, the conveyor belt automaticdishwasher 1 runs at a lower speed. Each operating mode, i.e. theoperating mode “Cleaning of dishes for milk products” or “Cleaning ofdishes for meat/meat products”, is assigned its own timer. The fourthswitch 74 is switched on in good time before the Sabbath. Correspondingfirst or second curtains 40 or 41 are to be suspended into the conveyorbelt automatic dishwasher 1. When the timer assigned to thecorresponding operating mode is switched on, the conveyor belt automaticdishwasher starts with the function filling/heating of the storage tank25 with water. When the desired temperature for rinsing is reached, therespective rinsing procedure begins, until the timer stops the rinsingprocedure. The first and second curtains 40, 41 are replaced by thethird curtains 42; the operating mode “Kosher operation” is then startedvia the timer. After completion of the operating mode “Kosheroperation”, a new rinsing procedure starts following the adjustments ofthe timer. To operate the conveyor belt automatic dishwasher 1 inworkday mode again, the fourth switch 74 is turned off.

If there is a power failure during the operating mode “Sabbathoperation”, or if the main switch is turned to off, then, after voltageis recovered after the power failure, the conveyor belt automaticdishwasher is switched back on via the machine control unit and a normaloperating mode “Sabbath operation” is resumed, i.e. the conveyor beltautomatic dishwasher 1 starts in the program sequence with filling andheating of the water tanks. If the belt limit switch function istriggered by a dish 51 striking against the limit switch 50, the limitswitch 50 is deflected downward and switches off the drive motor 49 ofthe drive mechanism 40 of the endless conveyor belt 10. The first lightbarrier 52 is disconnected. Every 15 seconds, the supply voltage of thefirst light barrier 52 is switched on via a short impulse. If it isfound that the limit switch 50 is free again, the forward movement ofthe endless conveyor belt in the direction of advance 11 begins. If, bycontrast, the limit switch 50 is not yet free, the supply voltage is cutout for another 15 seconds.

In the event of an emergency off function occurring, the conveyor beltautomatic dishwasher is switched off completely. The emergency offswitch is then switched to a voltageless state, and every 60 seconds animpulse of the supply voltage of the emergency off switch is switchedon. If this switch is released again, the program begins anew with thestep “Start/rinse operation on Sabbath”. If, at the time of theemergency off switch in the operating mode “Sabbath operation”, the“Kosher operation” is activated, the kosher mode runs afterdisconnection of the emergency off switch.

If, by contrast, the machine program at the time of the emergency offswitching is in the wash program in the operating mode “Sabbathoperation”, the wash program begins again, after disconnection of theemergency of f switch, with the step “Heating before kosher operation”.If, by contrast, the emergency off switch is not yet released, thesupply voltage is cut out for a further 60 seconds.

In the event of detection of an overload function, i.e. caused byobstruction of the forward movement of the endless conveyor belt 10 inthe direction of advance 11, the rinse operation is switched off and abelt overload switch is switched to a voltageless state. This is donevia the second light barrier 52. Every 30 seconds the supply voltage ofthe belt overload switch is switched on again by a short impulse. Ifthis switch is disconnected, the rinse operation starts, and if thecorresponding belt overload switch is not yet disconnected, the supplyvoltage is cut out for a further 30 seconds. This cycle can, forexample, be executed three times or more. If, after the third time, thebelt overload switch is still not free, the cycle is increased to 5minutes. If this cycle has again been completed three times withoutsuccess, the conveyor belt automatic dishwasher 1 is switched offcompletely and can also no longer be started again automatically in theoperating mode “Sabbath operation”.

LIST OF REFERENCE NUMBERS

-   1 automatic dishwasher with conveyor belt-   2 machine inlet-   3 preliminary clearing area-   4 coarse sieve-   5 fine sieve-   6 common outflow-   7 first rinse zone-   8 second rinse zone-   9 final rinse zone-   10 endless conveyor belt-   11 advance direction of material to be cleaned-   12 lower spray nozzles-   13 upper spray nozzles-   14 lower spray nozzles-   15 upper spray nozzles-   17 heat recovery module-   18 cooling register-   19 fan-   20 drying module-   21 dryer-   22 drying zone-   23 outlet for dishes-   24 drive mechanism of endless belt-   25 water tank-   26 dividing wall-   27 trough cover-   28 overflows-   29 circulating pump-   30 filter-   31 pump final rinse-   32 fresh water final rinse-   33 separation-   40 first curtain (operating mode Cleaning for milk products)-   41 second curtain (operating mode Cleaning for meat products)-   42 third curtain (operating mode “Kosher”)-   43 cleaning device for endless belt-   44 common outflow-   45 outflow for preliminary clearing area (separate)-   46 second outflow-   47 first filling line-   48 second filling line-   49 valve-   50 limit switch-   51 dish-   52 light barrier-   53 mirror surface-   54 housing-   55 connecting line-   56 bracket-   57 restoring spring-   58 opening-   59 drive motor-   60 tilt bearing for drive motor-   61 deflected position of limit switch 50-   70 control panel-   71 first switch for operating mode “Milk”-   72 second switch for operating mode “Meat”-   73 third switch for operating mode “Kosher operation”-   74 fourth switch for operating mode “Sabbath operation”

1. A method for operating an automatic dishwasher (1) with an endlessconveyor belt (10) which continuously conveys material to be cleaned andwhich is driven by a drive mechanism (24) controllable from a machinecontrol unit, and the automatic dishwasher (1) can be operated inseveral operating modes (71, 72, 73, 74), said method comprising thefollowing steps: a) on switching from a first operating mode (71)“Cleaning of dishes for milk products” to a second operating mode (72)“Cleaning of dishes for meat or meat products” and vice versa, executionof a third operating mode “Kosher operation” (73) is enforced, b) duringthe third operating mode (73) “Kosher operation”, the interior of theautomatic dishwasher (1) is cleaned with a cleaning fluid whosetemperature lies above the rinse water temperature or fresh watertemperature occurring in the normal operation of the automaticdishwasher (1), c) during the third operating mode (73) “Kosheroperation”, the endless conveyor belt (10) is cleaned continuously by acleaning device (43), d) during the third operating mode (73) “Kosheroperation”, the automatic dishwasher (1) is provided with a curtain (43)to be used exclusively in the third operating mode (73) “Kosheroperation”, and e) during a fourth operating mode (74) called “Sabbathoperation”, a cut-off function of the drive mechanism (24, 59) of theendless conveyor belt (10) is executed upon overloading and uponinterruption via light barriers (52).
 2. The method as claimed in claim1, characterized in that, in the third operating mode (73) “Kosheroperation”, the cleaning fluid for cleaning the areas of the automaticdishwasher contaminated in the first operating mode (71) or in thesecond operating mode (72) has a temperature of between 90° C. and 95°C.
 3. The method as claimed in claim 1, characterized in that, duringthe third operating mode (73) “Kosher operation”, the endless conveyorbelt (10) is cleaned continuously on the upper face and lower face by acleaning system (43).
 4. The method as claimed in claim 3, characterizedin that, in the third operating mode (73) “Kosher operation”, thecleaning system (43) is provided with a set of cleaning brushescorresponding to the preceding operating mode (71) or (72).
 5. Themethod as claimed in claim 1, characterized in that, in the firstoperating mode (71) “Cleaning of dishes for milk products”, only thefirst curtains (40) are suspended in the automatic dishwasher (1). 6.The method as claimed in claim 1, characterized in that, in the secondoperating mode (72) “Cleaning of dishes for meat products”, only thesecond curtains (41) are suspended in the automatic dishwasher (1). 7.The method as claimed in claim 1, characterized in that, on switchingfrom the first operating mode (71) “Cleaning of dishes for milkproducts” to the second operating mode (72) “Cleaning of dishes for meatproducts” and vice versa, the third operating mode (73) “Kosheroperation” is always executed.
 8. The method as claimed in claim 1,characterized in that, using a fourth switch (74) provided on thecontrol panel (70), the automatic dishwasher (1) can be converted to anoperating mode called “Sabbath operation” in which, if malfunctionsoccur, the drive mechanism (24, 59) of the endless conveyor belt (10)and of the circulating pumps (29) and of the fresh water supply line isautomatically switched off.
 9. The method as claimed in claim 8,characterized in that, in the fourth operating mode (74) of theautomatic dishwasher (1), a blocking of the advance movement (11) of theendless conveyor belt (10) is detected by a limit switch (50) configuredas a light barrier (52).
 10. The method as claimed in claim 9,characterized in that the detection of the blocked endless conveyor belt(10) is effected via a light barrier (52) which executes a currentinterruption function using a mirror which can be deflected via a leversystem (56) actuated upon blocking of the advance movement (11) of theendless conveyor belt (10).